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Critical latitudes are a significant area of tidal dissipation. Generally, critical latitudes are taken to be the exact latitude where the tidal frequency equals the inertial frequency. However, the key is really where the tidal frequency equals the combination of planetary vorticity and relative vorticity from background currents. Although the influence of background currents on critical latitude effects and nonlinear interactions have been noted for many years, their exact impacts are not well known. The latitude dependence of critical latitude impacts on the tides, internal tides, and internal waves in the presence of background currents was investigated using the Regional Ocean Modeling System by shifting a small domain including a seamount from 20.6° to 38.6°S and comparing simulations with and without background currents. The diurnal kinetic energy with mesoscale currents was relatively unchanged for most latitudes, except for a slight decrease 1–4° poleward of the critical latitude. However, the semidiurnal and high‐frequency (≥3 cycles per day) kinetic energy increased with the presence of mesoscale currents, especially within the diurnal critical latitude range. Spectral and nonlinear analyses indicated mesoscale currents broadened the range of critical latitude effects and enhanced energy transferring from diurnal frequencies to semidiurnal and high frequencies and from low to high mode waves. Local diffusivities increased, roughly an order of magnitude, when mesoscale currents were present. The impacts of mesoscale currents on the broadening of the critical latitude range and enhancement of nonlinear interactions were attributed to the additional relative vorticity and near‐inertial internal waves generated by mesoscale currents.

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